* {
  margin: 0;
  padding: 0;
}
a {
  text-decoration: none;
  color: white;
}
li {
  list-style: none;
}
.box {
  position: relative;
  width: 384px;
  height: 256px;
  margin: 0 auto;
  overflow: hidden;
}
#banner {
  position: absolute;
  width: 500%;
  height: 256px;
  /* transition: all 0.3s; */
}
#banner li {
  float: left;
}
#banner img {
  width: 384px;
  height: 256px;
}
.left , .right{
  display: none;
  position: absolute;
  top: 50%;
  transform: translateY(-50%);
  height: 20px;
  width: 15px;
  background-color: rgba(0,0,0,.5);
  text-align: center;
  line-height:18px;
  z-index: 2;
}
.right {
  padding-left: 3px;
  right: 0;
  border-top-left-radius: 50%;
  border-bottom-left-radius: 50%;
}
.left {
  padding-right: 3px;
  border-top-right-radius: 50%;
  border-bottom-right-radius: 50%;
}